1. Field of The Invention
The present invention relates to cleaning compositions having a viscoelastic rheology and, in particular, to hypochlorite compositions having a viscoelastic rheology which are formulated to have enhanced extensional viscosity.
2. Description of Related Art
Much art has addressed the problem of developing a thickened cleaning composition, which may contain a bleach and may have utility as a hard surface cleanser or a drain opener. The efficacy of such compositions is greatly improved by viscous formulations, increasing the residence time of the cleaner. Splashing during application and use is minimized, and consumer preference for a thick product is well documented. Schilp, U.S. Pat. No. 4,337,163, shows a hypochlorite thickened with an amine oxide or a quaternary ammonium compound, and a saturated fatty acid soap. Stoddart, U.S. Pat. No. 4,576,728, shows a shear-thinning thickened hypochlorite including 3- or 4-chlorobenzoic acid, 4-bromobenzoic acid, 4-toluic acid and 3-nitrobenzoic acid in combination with an amine oxide. Bentham et al., U.S. Pat. No. 4,399,050, discloses hypochlorite thickened with certain carboxylated surfactants, amine oxides and quaternary ammonium compounds. Citrone et al., U.S. Pat. No. 4,282,109, claims hypochlorite bleach thickened with a C.sub.10-18 amine oxide plus a C.sub.8-12 alkyl sulfate, and a ratio of amine oxide:sulfonate of at least 3:4.
Rorig et al, U.S. Pat. No. 4,842,771, discloses a tertiary amine oxide which may be C.sub.16 combined with cumene, xylene or toluene sulfonate, but also requires 1-5% of an acid, and the composition pH must not exceed about 6, thereby excluding alkaline cleaners. Rose, U.S. Pat. No. 4,800,036, describes viscoelastic hypochlorite solutions thickened with "onium surfactant ions" and aromatic sulfonate or carboxylate counterions. Stoddart, U.S. Pat. No. 4,783,283, describes a shear thinning hypochlorite containing composition containing 0.1% to 5% of a C.sub.12-15 amine oxide combined with 0.05% to 0.5% of an alkylated benzene or napthalene sulfonate. The disclosure of Stoddart is limited to the C.sub.15 chain length and the two specified aryl sulfonates.
Hunting, U.S. Pat. No. 3,560,389, discloses an unthickened hypochlorite bleaching composition utilizing an amine oxide and an alkylated benzene or naphthalene sulfonate. Hynam et al, U.S. Pat. No. 3,684,722, teaches thickening hypochlorite with an amine oxide and a soap. Neither of these references, teach or suggest a viscoelastic thickening system.